The invention relates to a tampon for feminine hygiene or medical purposes, and to a process for producing the same. The tampon, which is suitable for mass production, comprises a compressible tampon blank of liquid-absorbing material and an at least partial covering for the latter made of a liquid-permeable nonwoven material made of, at least partly thermoplastic, heat-sealable fibers, and is pressed into the final shape of the tampon.
Tampons customarily contain hydrophilic materials in the form of fibers or foams and are compressed into a generally cylindrical shape. It is known that the insertion of such a structure into the vagina is often difficult and uncomfortable because of the roughness and dryness of the surface texture of the absorbent core. If the absorbent core is also composed of fibrous materials, the fibers have the tendency to become detached during the insertion and the removal of the tampon from the body. Problems associated with insertion can be overcome to a certain extent by the use of an applicator for tampons that are provided for this; however, the use of applicators does not solve the problems associated with the loss of fibers or when removing the tampon. EP-B 0 149 155 and GB-B 1 218 641 relate to the use of a liquid-permeable covering layer, which encloses the absorbent core and reduces the fiber loss. In addition, the covering layer can reduce the surface friction by covering the absorption core located underneath it, and can contribute to more agreeable insertion and removal of the tampon.
Normally, the outer or covering layer itself is constituted by a nonwoven material, which has an essentially open, liquid-permeable structure and which is easier to produce (EP 0 149 155). In recent times, in many cases the covering layer materials have been developed in particular with regard to the improvement of the insertion properties, for example the covering consisting of polypropylene (PP) which is described in U.S. Pat. No. 3,683,912, or the powder-bonded material in Australian Patent 74346/91. In addition, it has been established that similar advantages can be achieved using materials other than nonwovens, such as network-like structures, which are described in U.S. Pat. No. 5,374,258. In a similar way, there are examples of covering layer or enveloping materials which have been developed in order to make the removal of the tampon easier. The absorbent core of the tampon is responsible for bringing about a high capillary suction in the vagina, as a result of which the removal of the tampon is often made more difficult and is disagreeable. Covering layers serving for easier removal solve this problem by means of methods of reducing the suction action, such as a more effective covering of the absorbent core, such as for the double-enveloped tampon which is described in U.S. Pat. No. 4,305,391, or by holding back liquid in the fibers of the covering layer in order to maintain a soft and supple surface, as in U.S. Pat. No. 4,056,103.
The present invention relates to a tampon and to processes for its production. The tampon according to the invention comprises an absorbent body of nonwoven fibers and a liquid-permeable, thermoplastic covering material which at least partly covers the latter and which is pressed radially to the final shape of the tampon. The covering material is fitted to the absorption body, and the entire structure is wound up to form a so-called tampon blank. The blank is pressed radially and a sharp taper may be formed at the insertion end, in order to impart the final form to the tampon.
Thermoplastic, nonwoven materials often constitute the desired material for tampon coverings, since they can easily be fastened to the tampon during production by applying heat and/or pressure (U.S. Pat. No. 4,863,450, which is herein incorporated by reference). Nonwoven materials which are produced from bicomponent fibers are particularly suitable for this process, since the polymer having the lower melting point, which forms one component of the fiber (often about 50% of the overall fibers in the form of a covering layer), melts, in order to form a fastening to the substrate lying beneath it, while the component having a higher melting point (often the fiber core) maintains its physical characteristic, in order to maintain the integrity of the covering.
An object of the invetnion is to improve a tampon, which is at least partly surrounded by a nonwoven covering tape, in such a way that, even before and after the days of relatively heavy menstruation, or in the case of only slight vaginal discharges occurring, it can be inserted more easily and more agreeably, as lingerie protection, into a body cavity and can also be removed again from the latter.
It has been established that smoothing the wholly or partially thermoplastic, nonwoven covering web by calendering under the influence of heat and pressure, this smoothing being integrated into the continuous mass production of tampons, provides a singular opportunity, without penalties in terms of production speed, to adapt the smoothing of the nonwoven covering web, by means of extremely fine control, to the respective tampon to be produced, and to optimize the said smoothing from the point of view of availability, quality requirements and quality control, reduction of waste and availability, for example from the point of view of necessary corrections to the dimensions.
Nonwoven materials comprising bicomponent fibers, or even nonwoven materials which are composed of a combination of fiber types having considerably different melting points and cross-sectional shapes, and which have either previously been bonded by calendering by means of a process such as air-laying or thermal bonding, or are supplied as a non-bonded web directly from a carder, can be led through the gap in a calender unit during the continuous mass production of tampons, the said calender unit being composed of two smooth rolls which apply pressure and temperature below the melting point to the fiber component having the lower melting point. The resulting material is a very smooth and glossy product, which not only provides the easing described during insertion, wearing and removal of the tampon, but in addition also has a pleasing appearance.